1. Field of the Invention
The present invention relates to liquid dehalogenating agents based on alkali metal alcoholates (alkoxides), the preparation of such dehalogenating agents, and the use of these dehalogenating agents for the dehalogenation of waste oils.
2. Discussion of the Background
Lubricating oils concentrate metallic dross and degradation and oxidation products of their constituents during use. Nevertheless, used lubricating oils are not considered to be waste products since they can be processed by filtration, distillation, or refining with concentrated sulfuric produced after replenishment of additives. However, contamination from chlorinated hydrocarbons, such as polychlorinated biphenyls (PCBs), for example, that are objectionable from the toxicological viewpoint, are not removed in this way.
It is known that contamination from organic halogen compounds in waste oils can be removed by treatment with alkali metal alcoholates. Thus, according to EP-B-21,294, alkali metal alcoholates of alcohols with 1 to 5 carbon atoms, polyoxyalkylene glycols with 4 to 20 carbon atoms, polyols with 2 to 5 carbon atoms and 2 to 3 hydroxyl groups, or of monoalkyl ethers of these polyols with alcohols with 1 to 4 carbon atoms, are disclosed as dehalogenating agents. The reaction is carried out in the presence of one-half to one equivalent of the related free alcohol. Dehalogenation is preferably carried out with sodium glycolate/ethylene glycol and with sodium methylate/methanol.
In DE-A-36 21 175, the dehalogenation of hydrocarbon oils is carried out with alkali metal alcoholates with 6 to 25 carbon atoms at 120 to 400.degree. C. The alcoholates in this case can contain small amounts of the related alcohol.
The known alcoholate dehalogenating agents are particularly sensitive to oxidation and hydrolysis at elevated temperatures. They also become solid or deposit solid constituents while cooling to room temperature. To avoid deposits, they have to be fed through heated pipes and pumps. In addition, they always have to be stored hot until they are used as intended.